There is also 'Hiccup and Astrid's Adventure'. This one takes them on a journey to a new land. The way it describes their interactions and how they rely on each other is really engaging. The author has a great writing style that makes you feel like you're right there with Hiccup and Astrid during their adventure.
There's also 'The Bond of Hiccup and Astrid'. This fanfiction takes a different approach. It focuses on their love through small, everyday moments. For example, how they train their dragons together and steal glances at each other. It's a very sweet and simple story that really shows their deep connection.
Archive of Our Own (AO3) is also a great place. It has a very inclusive and diverse set of fanfictions. Just search for 'httyd hiccup and astrid' and you'll get a bunch of results. The site also has good tagging systems so you can easily find stories with the elements you like, such as adventure or romance.
You can find it on fanfiction.net. There are a large number of stories dedicated to Astrid and Hiccup there. Just use the search bar and type in their names to start exploring.
Some fanfictions focus on their early days of getting to know each other. For example, a story where Hiccup is trying to teach Astrid more about Toothless and she is initially hesitant but then becomes fascinated, leading to a cute and heart - warming relationship development.
There would be a shift in their dynamic as they prepare for a family. Hiccup, who is used to being adventurous, would have to focus more on home and stability. Astrid, while still strong - willed, would become more nurturing. They would need to find a new balance in their relationship, between their old selves and their new roles as parents - to - be.
Another option is to search on Tumblr. There are often fanfic recs (recommendations) and some users may post their own fanfictions related to this topic. Just type in something like 'HTTYD 2 Hiccup and Astrid kiss fanfiction' in the search bar, and you might get lucky.
The relationship between Hiccup and Astrid is a big draw. Their dynamic in the movie is really interesting, and fans love to explore it further in fanfictions, especially a moment as significant as a kiss.
One great fanfiction could be 'A New Beginning'. It explores their married life as they face new challenges in Berk. Another is 'The Married Adventures' which focuses on their daily life and how they grow together. There's also 'Hiccup and Astrid: Ever After' which has a really heartwarming take on their married relationship.
It's popular because fans love seeing their favorite characters in a more developed relationship. Hiccup and Astrid are much - loved characters, and seeing them married gives a sense of completion to their story arcs.